Method of making ball cores



. I I I, II] I I hl r I I ll! 1 I I d [4 Nov. 21, 1944. G. RYAN 2,363,086-

METHOD OF MAKING BALL CORES Original Filed July 20, 1940 KR Q m 55 0/4 75 J? an 3 has matured into S me-o i m PATENT oth r 4 METHOD OF Gleorge K. Ryan, Akron, ohiofas signor to The p i l B. F, Goodrich Company, New York,- N. Y;.,a

corporation of New.York, l 1' Original application July 1 94B,* Serial No. 346,601, now Patent No.' 2,3=12,603,- dated February 22, 1944. J Divided-rand this application Septemberwi,1942;,SeriaL No. 457,292 r This invention relates toball cores, especially cores for: golf balls, although the "invention is useful in the manufacture of cores for baseballs and other typesof balls where high resiliencefor longflight following impact is desired. The in vention is directed more especially tonne con struction of the core, upon whichrubberthread or'tape is subsequentlywound underhigh tension.

This application is a division of myapplication SerlalNo; 346,601,1fild July 20, 1940; entitled Ball core andinethod of making the same and which Patent No. 2,342,603'of1ieb ruary 22, 1944 1 p '1" f It has been proposed-heretoforeto prcvidesuch coresby molding a shellofrubber upon a frozen pellet of a mixture of glue-j'glycerine or other substan-ceto provide a liquid centerythe shell being for the purpose of providing awinding surface for the rubber thread and retaining the liquid;

Such constructions, however, have not been fully satisfactory where it has beenfldesired to increase the internal liquid pressure Kin; the core of thecompleted ball-byneedle injection, there having' been no adequatefprovision"forpreventing j leakage through the, needle ope ng afterthe injection; In attempts to provide a seal for the needleit hasbeen"proposed-toprovide a villa canized rubber shell havingjan, inner layer of un-I vulcanized sealing compound; butflso far asIam aware no satisfactory way of ,utilizjingthis cone struction has been available especially with ref? ,erence to the problem, of providingjaliduid pellet accuratelyjcentered in such shelll lt has been exceedingly difficult to obtain true of a. pellet within. an unvulcanized mass, and be:

causeof this has been proposed to obtain the liquid center by needle injection of the squeezed shell with theaccompanying difiiculty of avoiding adhesion of the unvulcanized rubber as a result of such squeezing and with the further diifi culty of providinga suitably spherical core on which the winding of therubber thread could be effectively carried out.

Chief among the objectsof this invention are to provide a core construction and procedure for making the same, avoid or obviate theabove discussed and other difficulties which have existed in prior procedures, to provide a core that has a satisfactory degree of softness or distortability so that the elasticity of the winding upon it maybe fully availed of, together; with a firm surface of the core such that the winding [under high tenwhenthe completed ball isneed-led for increasing the internal pressure bylnjeCtiOn, and to effect suchsealing without requiring any specialitaping of thecore prior to winding the narrower elastic rubber thread. A further object is to provide these improved results: by a procedure that is convenient and suitable for rapid and economical manufacture. r L j 1' These andother objects will be apparent from the following description; reference being had to the following drawing, in which: i

Fig. 1 is a vertical section through a half-mold mounted in a vulcanizing press. i

Fig. 2 is a section taken along theline 2-2 of Fig. 3 is a view of a frozen pelletready for in corporation in the core. 1 i Fig.;4 is a view like Fig. 1, showing the half- 20 mold thereof associated withanotherhalf-mold in a vulcanizing press. Fig. 5 is aview like Fig. 4 but showing two halfmoldsdof larger cavity rubber thread has been applied.

Fig. 7, is a. view of the completed ball, parts Hbeing broken away to illustrate its construction, and a hollow needle being. shown through the vided the somewhat anomalous properties of a X 1 three principal parts, including a central liquid Y sion may be effected without cutting into such surface, to provide also ,for effectively scaling 551 wall. thereof forinjection to subject the ball to high internalipressurev i ,As hereinbefore stated the, invention is con cerned primarilywith the construction of the core upon which the elastic rubber thread is to.

be wound, In accordance with this inventionl provide for producing, a soft core, with its. in-

herent' advantages of making; possible a ball .capable 10f: long flight as: a result of' the distortion of the core, and elastic winding under impact, and thereis made possible a construction that will seal effectively after the injection needle has i been withdrawn. At the same time there is profirm surface of the core such that winding of the elastic thread thereupon is facilitated, together 7 with a core body that maintains its spherical shape during. handling in the manufacturing operations, and a permanent location of the parts thereof, concentrically disposed, without likelihood of settling or otherwise shifting of elements out of position.

To these ends I make th core preferably in center [0, a surrounding shell ll of softvulcanized rubber and an enclosing covering I2 of rela size used in a subsequent step of the procedure.

tively firm vulcanized rubber which, while being relatively stiff as compared to the soft rubber shell II, is highly resilient. The liquid center II), which may be of any suitable glue-Water or other mixture or liquid, may be provided in the form of a frozen pellet Illa. The soft rubber shell II may have a considerable amount of mineral oil or other softening agent incorporated in it but preferably is fully vulcanized so as to maintain its shape and support the liquid center concentrically therein. The firm character of the covering I 2 serves as a backing when the needle has been withdrawn after injection of the completed ball to resist outward flow of the center materials and to facilitate sealin by the soft rubber of the shell II, and the covering I2 serves also by its firm property to facilitate winding of the rubber thread immediately upon the same under high tension without undesirable cutting of its surface and without requiring a primary application of rubber tape as distinguished from narrow thread.

In order to obtain true concentricity of the pellet IIla within the shell II, the latter preferably is formed as two half-shells and partially vulcanized in such form before the introduction of the pellet. Such formation of each half-shell Ila is illustrated in Fig. 1 wherein a half-mold I3 with acover I4 defines a suitable cavity therebetween for producing the half-shell Ila. During the molding, heat may be supplied from steam jacketed press platens I5, l6 so that the halfshell I la will be semi-vulcanized to hold its shape when removed from the mold.

Two half-shells Ha, Ha, partially vulcanized are combined with a central frozen pellet Illa and placed in a mold shown in Fig. 4, which mold Such rubber'thread, indicated at 24, may be wound upon the core in any suitable manner,

shell H, while fully vulcanized and therefore lacking flowability in the sense of unvulcanized rubber, by coaction with the covering I2 of relatively firm rubber and the pressure of the supercomprises sections I3, IT. The mold may be held closed between heated platens I8, I9 a sufficient time for the halves of shell II to become firmly united and for the composition thereof to become nearly vulcanized, while nevertheless retaining its soft character. The shell thus formed is then placed in a mold of larger cavity together with a surrounding body of rubber to mold thereon the covering I2. This may be effected as shown in Fig. 5 in associated mold halves 20, 2 I, and again heated platens 22, 23 may be used to supply heat to vulcanize the rubber compositions in such mold. The composition of the covering I2 is preferably of a type that cures with comparative raimposed winding, is nevertheless effective to seal the needle openin and prevent the liquid of the center from following the needle and leaking out from th core. I

While the invention has been described with reference to the method of making golf balls, features thereof have been found useful also in the manufacture of other balls, such for example as baseballs where yarn rather than rubber thread is wound upon the core or center, but under tension thereon.

Variations may be made without departing from the scope of the invention as it is defined in the following claims. I

I claim: 7 a

1. The method of making a golf ball core suitable for high tension winding thereon and needle injection of the completed ball, comprising providing a congealed center pellet, forming and partially vulcanizing half shells of a mixture of rubber and. a softening agent, assembling the half shells about said center in a mold and applying heat and pressure to unite said halfshells to each other about said center while advancing vulcanization of the half shells, molding a covering of firm rubber composition about said half shells with said center pellet contained therein, and

fully vulcanizing said covering while completin the vulcanization of said half shells. I i

2. The method of making a golf ball core suitable for high tension winding thereon and needle injection of the completed ball, comprising providing a center-of frozen liquid, forming and partially vulcanizing half shells of a mixture of rubber and a mineral oil, assembling the half shells about said center in a mold and applying heat and pressure to unite said half shells to each other about said center while advancing vulcanization of the half shells, molding a covering of firm rubber composition about said half shells and said center, and fully vulcanizing said covering while completing the vulcanization of said half .shells.

, GEORGE K. RYAN. 

